Aircraft monitoring system and method for collecting data on aircraft maintenance

ABSTRACT

An aircraft monitoring system which includes: at least one Line Replaceable Unit (LRU) installed in an aircraft unit, the LRU comprising a Radio Frequency Identification (RFID) tag, the RFID tag containing stored information which consists of or comprises ID-information identifying the LRU; and an RFID reader installed in the aircraft unit, the RFID reader being configured to at least intermittently automatically read the RFID tag of the at least one LRU. The RFID reader is configured to transmit at least the read ID-information to an aircraft communication unit that participates in sending the ID-information to a remote surveillance system. Further aspects of the invention regard a method and a surveillance system for collecting data on aircraft maintenance.

The invention regards an aircraft monitoring system and a method forcollecting data on aircraft maintenance.

A Line Replaceable Unit (LRU) is a modular component of a manufactureddevice that is designed to be replaced quickly and individually at anoperating location. In the context of aircrafts, an LRU is a unit thatcan be removed and re-fitted from an aircraft in field.

Typically, LRUs are replaced by aircraft mechanics from airlines or fromthird parties due to faulty conditions demonstrated by these units. Afaulty condition is usually presented by a malfunction of a system ormaintenance fault code shown in the aircraft cockpit. In an aircraftengine, this fault is generated by the Electronic Engine Control (EEC)unit (which is an LRU by itself) that monitors health status from theother LRUs and issues a fault code to the cockpit. This fault code isthen addressed by line maintenance troubleshooting described in a FaultIsolation Manual (a part of the Aircraft Maintenance Manual).

Typically, part of the troubleshooting is to remove the LRU, send it torepair or troubleshooting quarantine and install a serviceable LRU.During this removal installation transaction important information canbe obtained like the LRU component accumulated hours and cycles, thelocation of removal, the environment it operated in, the time it tookthe mechanics to remove the LRU and install a new LRU, etc.

An LRU removal and replacement may be not digitally recorded at all, itmay be digitally recorded after the fact (up to a few weeks) or it maybe digitally recorded in a format not compatible with formats andsoftware used by the aircraft engine manufacturer. It may also be thecase that some parameters that are important to the aircraft enginemanufacturer are not recorded at all. All this generates a high amountof extra efforts to track LRU components and to obtain the requiredinformation about replaced LRUs, and in many cases this task cannot beaddressed properly. At the same time, asset management is essential toensure product support over its lifecycle.

For product supportability it is essential to have a clear view on thereliability of units coped with its operational environment, unit age,maintainability information and root cause understanding of failures.For such a close understanding of asset location is necessary.

Document US 2016/0196457 A1 discloses an LRU health node having an RFIDmodule and sensors that monitor operational parameters of several LRUs.The LRU health node gathers data on the LRUs and stores the data locallyin a mass storage memory. The stored data can be read by an RFID scannerwhich may determine a maintenance action by forwarding the data over adigital network to a remotely located maintenance support center. US2016/0196457 A1 thus discloses the use of a single RFID tag for storinghealth information about various components of an aircraft engine.

The problem underlying the present invention is to provide systems andmethods that improve lifecycle management of LRUs of aircraft units.

This problem is solved by an aircraft monitoring system with thefeatures of claim 1, a method for collecting data on aircraftmaintenance with the features of claim 13, a surveillance system forcollecting data on aircraft maintenance with the features of claim 17and a software application product with the features of claim 21.Embodiments of the invention are identified in the dependent claims.

According to an aspect of the invention, an aircraft monitoring systemis provided which comprises at least one Line Replaceable Unit (LRU)installed in an aircraft unit. The LRU comprises a Radio FrequencyIdentification (RFID) tag. The RFID tag contains stored informationwhich consists of or comprises identification information(ID-information) identifying the LRU. The aircraft monitoring systemfurther comprises an RFID reader installed in the aircraft unit, theRFID reader being configured to at least intermittently automaticallyread the RFID tag of the at least one LRU. Further, the RFID reader isconfigured to transmit at least the read ID-information to an aircraftcommunication unit that participates in sending the ID-information to aremote surveillance system.

The invention thus provides for a maintenance system in which RFID tagsare included in the LRUs, wherein the RFID tags identify the LRUs, andin which the RFID tags are read by an RFID reader installed in theaircraft unit automatically and at least intermittently. The capturedinformation/data is transmitted to a remote surveillance system. Theinvention allows to identify any replacements of LRUs as, after areplacement, the ID of the LRU has changed. The invention thus providesfor an automatic and service personal independent means to identify at aremote surveillance system when an aircraft LRU was removed and a newone has been installed. The remote surveillance system may be a unitassociated with the manufacturer of the aircraft unit. It may be acentral or decentralized computer system.

The automatic capture of an aircraft unit LRU replacement that occurs inthe course of a service operation may be used for different purposes ina company, such as reliability assessments and lifecycle management.

Another advantage associated with the invention lies in that, as the LRUis identified by an RFID tag, it is not necessary anymore to printidentification codes such as a barcode, a QR code or a data matrix codeon the LRU.

In an embodiment of the invention, the aircraft unit in which the LRUsand the RFID reader are installed is an aircraft engine (such as aturbofan engine). However, the invention is not limited to suchembodiment. In other embodiments, e.g., the aircraft unit in which theLRUs and the RFID reader are installed is a Landing Gear Unit (the LRUsbeing, e.g., hydraulic pumps or hydraulic actuators) or an EngineVibration Monitoring Unit (the LRUs being, e.g., accelerometersinstalled in the aircraft that acquire and process signals).

The RFID reader is configured to automatically read the RFID tags of theLRUs at least intermittently. In an embodiment of the invention, theRFID reader is configured to read the RFID tag periodically. The term“periodically” is to be understood in a broad manner. It may mean thatthe RFID tags are read after defined time intervals but it may also meanthat the RFID tags are read triggered by any event that occursrepeatedly. For example, it may be provided that the RFID reader isconfigured to read the RFID tag upon each start of the aircraft oraircraft engine. This provides for an efficient reading of the RFID tagsas the start of the aircraft is the first time an LRU is used aftermaintenance and possible replacement of the LRU.

The RFID tag may be a passive or semi-active tag according to someembodiments of the invention. Alternatively, it may be an active tag.Active and semi-passive RFID tags use internal batteries to power theircircuits. An active tag also uses its battery to broadcast radio wavesto a reader, whereas a semi-passive tag relies on the reader to supplyits power for broadcasting. Which kind of RFID tag to use depends on theavailable signal strength. For example, if the RFID reader which is at afixed location in the aircraft unit is distant from the LRU and/orshielding components are located between the RFID reader and the LRU, itmay be preferable to use a semi-active tag rather than a passive tag.Naturally, passive tags are preferred for cost reasons if the signalstrength they provide is sufficient for a safe reading.

The RFID tags used in the present invention are of conventional designas well known to the skilled person. In particular, an RFID tag maycomprise the following elements: an integrated circuit that isconfigured to store and process information that modulates anddemodulates radio-frequency signals; a circuit that is configured tocollect power from a reader signal that is incident and/or a battery;and an antenna that is suitable to receive and transmit the signal. Thetag information is stored in a memory. The tag information includesID-information that identifies the LRU to which the tag is attached orinto which it is integrated. The tag information may consist solely ofID-information in the simplest form of the invention. ID-information maybe, e.g., a unique tag serial number or the like. Alternatively,additional information about the LRU may be stored in the RFID tag. Inan exemplary embodiment of the invention, the RFID tag is embedded inhardware of the LRU. This avoids the risk that the RFID tag may bedislocated from the LRU.

The RFID reader may be located at any suitable location within theaircraft unit. Due to the fact that the read information is transmittedto an aircraft communication unit that participates in sending theID-information to a remote surveillance system, the RFID reader islocated in an exemplary embodiment of the invention inside, outside ornear an Electronic Control Unit of the aircraft unit (such as theElectronic Engine Control (EEC) in case of an aircraft engine), whereinthe Electronic Control Unit unit represents such aircraft communicationunit. More particularly, the RFID reader may be integrated with otherelectronic components inside the Electronic Control Unit. Alternatively,the RFID reader may be separate component from the Electronic ControlUnit and be located outside of the Electronic Control Unit (it may,e.g., be attached to the housing of the Electronic Control Unit) or belocated near the Electronic Control Unit. In the latter cases, it may beprovided that the RFID reader is wire connected to the ElectronicControl Unit and that the RFID reader and the Electronic Control Unitcommunicate via a bus. Further, it is pointed out that in otherembodiments the RFID reader may located remote from the ElectronicControl Unit in the aircraft, e.g., in the engine nacelle, in the pylonor in the aircraft fuselage.

It is pointed out that a considered aircraft unit such as an aircraftengine may have one or several RFID readers, each RFID reader reading atleast intermittently and automatically the RFID tag of at least one LRU.If several RFID readers are present in a unit, each RFID reader can readthe RFID tags of the LRUs closest to it, thereby ensuring sufficientsignal strength for the communication between readers and tags.

It is further pointed out that within the meaning of the presentinvention an RFID reader is considered a part of and installed in anaircraft unit when it is able to read signals of RFID tags of LRUs ofthat unit.

According to an exemplary embodiment, the aircraft communication unit towhich the RFID reader transmits the information read from the RFID tagis an electronic control unit of the aircraft unit (such as theElectronic Engine Control (EEC) in case of an aircraft engine) or anon-board communication unit located in the aircraft. Accordingly, in oneembodiment the information read by the RFID reader is transmitted tosuch electronic control unit. Typically, the electronic control unitcommunicates with an on-board communication unit that sends theinformation to ground. In another embodiment, the information read bythe RFID reader is transmitted directly to such on-board communicationunit without the information passing through the electronic controlunit. To this end, a direct communication is established in such casebetween the RFID reader and the on-board communication unit which may bea wire based or wireless communication.

In an embodiment of the present invention, the aircraft communicationunit to which the RFID reader transmits the ID-information read from theRFID tag (which may be an electronic control unit such as the EEC or anon-board communication unit as mentioned above) is designed andconfigured to participate in transmitting the read ID-information to theremote surveillance system by means of an Health Monitoring system thathas been implemented to transmit health information about aircraftcomponents to the remote surveillance system. Such Health Monitoringsystem is state of the art. The idea of such Health Monitoring system isto collect data about engine or other aircraft components throughsensors and to transmit these data to ground to a surveillance system.Such transmission may take place, e.g., through a wireless local areanetwork if the airplane is on ground, or take place, e.g., throughsatellite communication if the airplane is in the air. The health datais typically collected at an electronic control unit such as the EEC andtransmitted from the electronic control unit to an on-boardcommunication unit located in the aircraft, from which it is transmittedto ground.

According to the mentioned embodiment of the invention, the datatransmission through the Health Monitoring system is used also totransmit the ID-information (and, if present, further information storedin the RFID tag) read from the RFID tags to the remote surveillancesystem. This is associated with the advantage that no additional datatransmission system has to be established.

As mentioned, the read information allows to identify any replacementsof LRUs as, after a replacement, the ID of an LRU has changed. Inprincipal, the logical evaluation and analysis that an LRU has beenreplaced may take place either at the RFID reader itself (ifsufficiently intelligent), at the aircraft communication unit (e.g., theEEC) and/or at the remote surveillance system. According to anembodiment of the invention, it is the aircraft communication unit towhich the RFID reader transmits the ID-information that is configured todetermine from the ID-information if an LRU has been replaced. In caseof such replacement, the replacement information is transmitted togetherwith the read ID-information to the remote surveillance system. Theintelligence to determine if an LRU has been replaced is thus located inthe EEC or in another aircraft unit. This is associated with theadvantage that, if a replacement is detected, additional informationabout the replaced LRU present at the aircraft unit may be sent to theremote surveillance system along with the ID-information.

According to a further embodiment, the communication unit is alsoconfigured to link ID-information regarding an LRU (or a replacementinformation deducted from such ID-information) with at least one of thefollowing additional information: accumulated hours and/or cycles of theLRU before removal, location of removal of the LRU, and time of removalof the LRU. Such additional information that is linked to the IDinformation may be available through sensors or other devices or may bededucted from the replacement information. For example, the accumulatedhours and/or cycles of an LRU may be determined from the time intervalbetween installation of the LRU and its replacement that has just beendetermined. The location of removal may be determined by a GPS unitincluded in the electronic control unit or somewhere else in theairplane. The time of removal may be approximated by the time at whichthe RFID tag of an LRU is read by an RFID reader.

The additional information may be transmitted together with the readID-information and/or the replacement information to the remotesurveillance system such that the remote surveillance system hasadditional information about the LRUs to improve lifecycle management.

According to a further aspect of the invention, a method for collectingdata on aircraft maintenance is provided, the method comprising:

-   -   automatically reading at least intermittently by means of an        RFID reader which is located in an aircraft unit ID-information        contained in at least one Radio Frequency Identification (RFID)        tag comprised in a Line Replaceable Unit (LRU) of the aircraft        unit, each RFID tag containing ID-information identifying the        respective LRU, and    -   transmitting the read ID-information to a remote surveillance        system.

In an exemplary embodiment of method, the read ID-information istransmitted to the remote surveillance system by means of a HealthMonitoring system that transmits health information about aircraftcomponents from the aircraft to the remote surveillance system. SuchHealth Monitoring system may be an Engine Health Monitoring system.

The ID information read from the RFID tag is interpreted to determine ifan LRU of the aircraft unit has been replaced. As discussed before, suchdetermination may be made at different points, e.g., at an EEC or theremote surveillance system. In any case, the replacement information isgathered at the remote surveillance system.

In an embodiment, the aircraft unit is an aircraft engine such that themethod is a method for collecting data on aircraft engine maintenance.

According to a further embodiment of the method, ID-informationregarding an LRU (or a replacement information deducted therefrom) islinked with at least one of the following additional information:accumulated hours and/or cycles of the LRU before removal, location ofremoval of the LRU, time of removal of the LRU, and time to remove theLRU and install a replacement LRU. Such additional information that islinked to the ID information may be available through sensors or otherdevices or may be deducted from the replacement information. Further,such additional information may be provided by an aircraft mechanic. Forexample, when replacing an LRU, an aircraft mechanic may note the timeto remove the LRU and install the replacement LRU. This information maybe linked to the ID of the LRU.

According to a further aspect of the invention, a surveillance systemfor collecting data on aircraft maintenance is provided, wherein thesurveillance system is configured to receive from an aircraftcommunication unit ID-information regarding at least one LRU of anaircraft unit (such as an aircraft engine), wherein each ID-informationis contained in an RFID tag of an LRU and identifies an LRU. Thesurveillance system is further configured to determine from the receivedID-information if an LRU has been replaced by a new LRU. In this aspectof the invention, the intelligence to determine if an LRU has beenreplaced is located in the surveillance system.

To carry out the mentioned operations, the surveillance system maycomprise a processor and a memory communicatively coupled with theprocessor, the memory storing instructions which, when executed by theprocessor, perform the mentioned operations of receiving from anaircraft communication unit ID-information regarding at least one LRU ofan aircraft unit and of determining from the received ID-information ifan LRU has been replaced.

According to an embodiment of the surveillance system, the surveillancesystem is further configured to link a replacement information regardingan LRU with at least one of the following additional information:accumulated hours and/or cycles of the LRU before removal, location ofremoval of the LRU, time of removal of the LRU, time to remove the LRUand install and replacement LRU. As mentioned before, such additionalinformation may be available through sensors or other devices, may bededucted from the replacement information, or may be made availablethrough aircraft mechanics or other service personal.

Accordingly, one exemplary embodiment provides that the surveillancesystem is further configured to provide ID-information or informationdeducted therefrom (such as troubleshooting instructions) to servicepersonal units (which may be a mobile device such as a smartphone ortablet computer with an appropriate app installed) for use of suchinformation by service personal when maintaining the LRU, and to receivefrom such service personal units additional information about LRUs andmaintenance work performed thereon. According to this aspect, thesurveillance system is thus further configured for a communication toand from service personal units, wherein such communication serves tocollect additional data about an LRU and/or to use the received IDinformation on replaced LRUs to improve maintenance services.

A further embodiment provides that the surveillance system is furtherconfigured to receive information from a stock or repair facility abouta replaced LRU, the stock or repair facility identifying a replaced LRUby means of its RFID tag. Thereby, additional information about thepresent location of a replaced LRU can be collected at the surveillancesystem.

According to a still further aspect of the invention, a softwareapplication product is provided that is storable and operable in amobile device that includes a graphical user interface, the softwareapplication product when executed on a processor in the mobile devicebeing operative to:

-   -   receive from a remote surveillance system information on at        least one Line Replaceable Unit (LRU) of an aircraft unit that        has been or that shall be replaced, the information including        identification (ID) information contained in a Radio Frequency        Identification (RFID) tag comprised in the LRU,    -   provide to the remote surveillance system information about such        LRU (e.g., condition upon removal, visible damages or colour        changes, etc.) and/or maintenance work performed thereon (e.g.,        time spent to replace).

The mobile device includes a non-transitory computer-readable mediumstoring instructions for operating the mobile device, wherein theinstructions, when executed by one or more processors of the mobiledevice, cause the processors to perform operations in the mobile devicethat comprise the mentioned operations.

This aspect of the invention provides for an app in a mobile device of aservice personal that allows communication between the mobile device andthe remote surveillance system with respect to information regarding anLRU that has been or that is to be replaced.

The invention will be explained in more detail on the basis of exemplaryembodiments with reference to the accompanying drawings in which:

FIG. 1 is a simplified schematic sectional view of a turbofan engine inwhich the present invention can be realized;

FIG. 2 shows schematically an embodiment of an aircraft enginemonitoring system that comprises Line Replaceable Units (LRUs) eachhaving an RFID tag, a RFID reader, an Electronic Engine Control (EEC)unit, in airplane communication unit and a remote surveillance system;

FIG. 3 shows the LRUs, the RFID reader and the EEC of FIG. 2 in moredetail;

FIG. 4 is a flowchart of a method to transmit information stored in RFIDtags to a remote surveillance system; and

FIG. 5 is a flowchart of a method to determine from information receivedfrom RFID tags if an LRU has been replaced.

FIG. 1 shows, in a schematic manner, a turbofan engine 100 that has afan stage with a fan 104 as the low-pressure compressor, amedium-pressure compressor 111, a high-pressure compressor 112, acombustion chamber 113, a high-pressure turbine 114, a medium-pressureturbine 115, and a low-pressure turbine 116.

The medium-pressure compressor 111 and the high-pressure compressor 112respectively have a plurality of compressor stages that respectivelycomprise a rotor stage and a stator stage. The turbofan engine 100 ofFIG. 1 further has three separate shafts, a low-pressure shaft 118 thatconnects the low-pressure turbine 116 the fan 104, a medium-pressureshaft 119 that connects the medium-pressure turbine 115 to themedium-pressure compressor 111, and a high-pressure shaft 120 thatconnects the high-pressure turbine 114 to the high-pressure compressor112. However, this is to be understood to be merely an example. If, forexample, the turbofan engine has no medium-pressure compressor and nomedium-pressure turbine, only a low-pressure shaft and a high-pressureshaft would be present.

The turbofan engine 100 has an engine nacelle 101 that comprises aninlet lip 102 and forms an engine inlet 103 at the inner side, supplyinginflowing air to the fan 104. The fan 104 has a plurality of fan blades107 that are connected to a fan disc 106. The annulus of the fan disc106 forms the radially inner boundary of the flow path through the fan104. Radially outside, the flow path is delimited by the fan housing108. Upstream of the fan-disc 106, a nose cone 105 is arranged.

Behind the fan 104, the turbofan engine 100 forms a secondary flowchannel 109 and a primary flow channel 110. The primary flow channel 110leads through the core engine (gas turbine) that comprises themedium-pressure compressor 111, the high-pressure compressor 112, thecombustion chamber 113, the high-pressure turbine 114, themedium-pressure turbine 115, and the low-pressure turbine 116. At that,the medium-pressure compressor 111 and the high-pressure compressor 112are surrounded by a circumferential housing 117 which forms an annulussurface at the internal side, delimitating the primary flow channel 110radially outside.

During operation of the turbofan engine 100, a primary flow flowsthrough the primary flow channel 110, which is also referred to as themain flow channel, and a secondary flow flows through the secondary flowchannel 109, which is also referred to as bypass channel, wherein thesecondary flow bypasses the core engine.

The described components have a common rotational or machine axis 200.The rotational axis 200 defines an axial direction of the turbofanengine. A radial direction of the turbofan engine extendsperpendicularly to the axial direction.

Furthermore, the turbofan engine 100 comprises an Electronic EngineControl (EEC) unit 2 which is depicted schematically. The EEC unit 2 isa digital control unit that combines engine sensor information withcockpit instructions to ensure that the engine performs both safely andat an optimal level. It is typically mounted to the fan case of anengine. In the described embodiment, the EEC unit 2 is connected to anRFID reader 3 that automatically reads RFID tags of Line ReplaceableUnits (LRUs) of the turbofan engine, as will be explained in relation toFIGS. 2-5.

It is pointed out that the aircraft engine of FIG. 1 represents just oneexample of an aircraft engine in which the invention may be implemented.Other examples regard one shaft or three shaft turbofan engines andturboprop engines.

FIG. 2 shows an exemplary embodiment of an aircraft engine monitoringsystem. The monitoring system comprises a plurality, in the depictedcase three LRUs 41, 42, 43 which are located in an aircraft engine 100.An LRU is a unit that may be removed and re-fitted from the aircraftengine 100 in field, i.e., without completely dismantling the aircraftengine or taking it to a workshop. The LRU may be a sealed unit. It mayhave standardized connections for rapid mounting, cooling air, power,and grounding. A plurality of components of an aircraft engine qualifiesor may qualify as an LRU. Examples for LRUs include mechanical unitssuch as a valve or a hydraulic pump, electrical units such as a switchor relay and electronic units such as an Air Turbine Starter or anElectronic Engine Control (EEC) unit.

Each LRU 41, 42, 43 is associated with an RFID tag 51, 52, 53. The RFIDtag contains information that identifies the tag and thus the LRU towhich the tag is connected or into which it is integrated. Suchinformation is referred to as ID-information. Optionally, several IDsmay be included in the RFID tags for separately identifying the RFID tagand the LRU associated with the RFID tag. In the context of the presentinvention, such several IDs are also referred to as ID-information. TheRFID tags 51, 52, 53 may include further information such as informationon parameters or characteristics of the LRU.

In one embodiment, the RFID tags 51, 52, 53 are embedded in hardware ofthe LRUs 41, 42, 43 such that the RFID tags and the LRUs cannot bephysically separated.

The aircraft engine monitoring system further comprises an RFID reader 3which is also installed in the aircraft engine 100 and a fixed part ofthe aircraft engine 100. The RFID reader 3 is located and configuredsuch that it is able to read the RFID tags 51, 52, 53 of all LRUs 41,42, 43 that are located in the aircraft engine 100. Depending on thesignal strength, the RFID tags 51, 52, 53 may be passive, semi-active oractive tags. The signal strength is to be adjusted such that the RFIDreader 3 can read the information of all RFID tags 51, 52, 53.

Alternatively, two or more RFID readers are installed in the aircraftengine, each reader provided and configured to read a subset of the RFIDtags of the engine LRUs.

The RFID tags 51, 52, 53 may broadcast and the RFID reader 3 may receivefrequencies in any of the known RFID frequency bands (low frequency band(LF, 120-150 kHz), high frequency band (HF, 13.56 MHz), ultrahighfrequency band (UHF, about 850 to 950 MHz), or a microwave band).

The RFID tags 51, 52, 53 may be of conventional design. In particular,an RFID tag may comprise an integrated circuit for storing andprocessing information that modulates and demodulates radio-frequencysignals, a circuit for collecting DC power from an incident readersignal and/or a battery, and an antenna for receiving and transmittingthe signal. The tag information is stored in a memory. In a similarmanner, the RFID reader 3 may be of conventional design. The RFID reader3 may be an active reader or a passive reader depending on the design ofthe RFID tags.

The aircraft engine monitoring system further comprises an ElectronicEngine Control (EEC) unit 2. As mentioned, the EEC unit 2 is a digitalcontrol unit that combines engine sensor information with cockpitinstructions to ensure that the engine performs both safely and at anoptimal level. As all other components, the EEC 2 is depicted onlyschematically.

In the embodiment depicted in FIG. 2, the RFID reader 3 is a separatecomponent from the EEC 2. In alternative embodiments, the RFID reader 3may be integrated into the EEC 2. Further, it is pointed out that theEEC 2 is also an LRU. It may be provided with an RFID tag in a similarmanner als LRUs 41, 42, 43.

The EEC unit 2 communicates with an aircraft on-board communication unit60 that is located in the aircraft 6. The communication may be by serialbus. The on-board communication unit 60 is designed and configured totransmit information received from the EEC unit 2 and/or otherinformation to ground. The respective communication may take place via awireless local network or telecommunication network if the aircraft ison ground and may take place via satellite communication if the aircraftis in the air. Information gathered by the RFID reader 3 is transmittedfrom the RFID reader 3 to the EEC to and from the EEC 2 to the on-boardcommunication unit 60. From the on-board communication unit 60, thisinformation is transmitted to the remote surveillance system 7 which maybe the surveillance system of the manufacturer of the aircraft engine100. The information transmitted to the remote surveillance system 7 mayinclude additional information such as health information about the LRUscollected by sensors of the EEC 2, as will be discussed in the nextparagraph.

In an embodiment the transmission of information from the on-boardcommunication unit 60 to the remote surveillance system 7 takes place bymeans of an engine health monitoring system that is implemented betweenthe aircraft (the EEC 2 and the on-board communication unit 60) and theremote surveillance system 7 to provide the remote surveillance system 7with health information about the components of the aircraft engine 100.Such engine health monitoring systems are well known and described,e.g., in US 2016/0177856 A1. One purpose of such engine healthmonitoring system is to improve long-term scheduling of aircraft enginemaintenance.

It will be appreciated that the transmission of information from theon-board communication unit 60 to the remote surveillance system 7 mayinclude a plurality of intermediate nodes and communication links thatare not described as they are not relevant for the present invention andcomprised in the state of the art. In this sense, the on-boardcommunication unit 60 as well as the EEC 2 participate in sending the IDinformation to the remote surveillance system 7.

A method of collecting data on aircraft engine maintenance by means ofthe aircraft engine monitoring system of FIG. 1 is explained withrespect to FIG. 4. The RFID reader 3 is configured to read at leastintermittently and automatically the RFID tags 51, 52, 53 of the LRUs41, 42, 43 located in the aircraft engine 100. For example, such readingtakes place upon each start of the aircraft engine. This way, it can bedetermined if an LRU has been replaced while the aircraft has been onthe ground. Alternatively, the RFID reader may be configured to read theRFID tags 51, 52, 53 in different intervals, such as fixed timeintervals. In principle, it can also be provided that the RFID reader 3reads the RFID 51, 52, 53 tags in very short time intervals and thusessentially continuously.

Accordingly, in step 401 of FIG. 4 a reading session is started with thestart of the aircraft engine 100. In step 402, the RFID tags 51, 52, 53are read by means of the RFID reader 3. The read information includesID-information that identifies the respective LRUs 41, 42, 43. At leastthis ID-information is sent from the RFID reader 3 to the EEC 2. To thisend, the RFID reader 3 may be connected by wire with an input port ofthe EEC 2.

The read information is transmitted in step 403 of FIG. 4 to the remotesurveillance system 7. To this end, the information is sent from the EEC2 to the aircraft on-board communication unit 60 and from the aircrafton-board communication unit 60 to the remote surveillance system 7 inthe manner discussed above.

By reading the ID-information of the LRUs, a determination can be madeif an LRU has been removed and replaced by another LRU duringmaintenance work. This can be determined in a simple manner bydetermining if an LRU ID that has been read during the previous readingof the RFID tags is now missing and a new LRU ID is present. Thisanalysis can be carried out in the aircraft engine 100 or at the remotesurveillance system 7. Accordingly, in one embodiment the determinationif an LRU has been replaced is made in the EEC 2. In another embodiment,such determination is made in the remote surveillance system 7. Therespective method is the same in both cases and depicted by example inFIG. 5.

According to FIG. 5, the analysis is started by the reading of the RFIDtags 51, 52, 53 of the LRUs 41, 42, 43, step 501. In step 502, the readIDs of the LRUs are compared with the previously read IDs of the LRUs.In step 503, if the ID of an LRU has changed, it is determined that theLRU has been replaced. In embodiments of the invention, this replacementinformation is linked with other available information related to theLRU. For example, the replacement information may be linked withinformation on accumulated hours and/or cycles of the LRU beforeremoval, with information on the location of removal of the LRU and/orwith information on the time of removal of the LRU. This additionalinformation may be provided by sensors that are connected to the EECunit 2, as will be explained with respect to FIG. 3. In step 505 of FIG.5, the linked information is used for reliability assessments andlifecycle management in the remote surveillance system 7.

In one embodiment, the remote surveillance system 7 may receiveadditional information from an aircraft mechanic 80 who is maintainingthe LRUs 41, 42, 43 on ground. Such aircraft mechanic 80 is alsodepicted in FIG. 2. The aircraft mechanic 80 has a mobile device 8 suchas mobile phone or a tablet computer which is in communication with theremote surveillance system 7. The mobile device 8 has installed thespecific app that allows the aircraft mechanic 80 to communicate withthe remote surveillance system 7.

In particular, the aircraft mechanic 80 may sent by means of the mobiledevice 8 information to the surveillance system 7 regarding thecondition of an LRU when being replaced or the time it took to replacethe LRU. To identify an LRU, the mobile device may include or be coupledto an RFID reader that allows to read an RFID tag 51, 52, 53 by theaircraft mechanic 80. Further, the aircraft mechanic 80 may receivethrough the mobile device 8 information from the surveillance system 7about specific LRUs and maintenance work to be performed thereon. Suchinformation on maintenance work to be performed may depend on theinformation provided by the RFID reader 3.

FIG. 3 shows the LRUs 41, 42, 43, the RFID tags 51, 52, 53, the RFIDreader 3 and the EEC 2 of FIG. 2 in more detail. More particularly, eachLRU 41, 42, 43 is associated with one or several sensors 91, 92, 93which are provided and configured to sense operational and health dataof the LRUs 41, 42, 43.

The data sensed by the sensors 91, 92, 93 are provided to the EEC unit2. More particularly, the EEC unit 2 comprises a controller 21 whichreceives the data from the sensors 91, 92, 93 and which also receivesthe data read by the RFID reader 3. The EEC unit 2 further comprises apower source 23, a mass storage memory 22 in communication with thecontroller 21 and in interface 24 for sending data to the aircrafton-board communication unit 60 of FIG. 2. It is pointed out that onlythe components of the EEC unit 2 relevant for the present invention aredepicted in FIG. 3. The EEC 2 is a unit with further components andfunctionalities as known to the skilled person.

The RFID reader 3 comprises a reader 31 which transmits interrogatorsignals and also receives authentication replies from tags 51, 52, 53.The RFID reader 3 further comprises a temporary memory 32 in which,according to an embodiment, the received information is stored until ithas been transmitted to the EEC unit 2. The RFID reader 3 may compriseadditional components such as a battery.

The sensors 91, 92, 93 sense operational or health data of the LRUs 41,42, 43 that are stored in memory 22 of the EEC unit 2. This health datacan be linked to the ID-information provided by the RFID reader 3. Forexample, if the EEC unit 2 determines that one of the LRUs, e.g., LRU 41has been replaced, it will provide the health data collected withrespect to the now replaced LRU to the remote surveillance system 7together with the ID-information. The linking of the health informationto the information that the LRU has been replaced may take place at thelevel of the EEC unit 2 or at the level of the remote surveillancesystem 7. Further information may be linked to the ID-information inparticular at the level of the remote surveillance system 7 as discussedabove.

It should be understood that the above description is intended forillustrative purposes only, and is not intended to limit the scope ofthe present disclosure in any way. For example, the manner in which theread ID-information is transmitted to a remote surveillance system 7 isdescribed by example only. Alternative ways to transmit information tothe remote surveillance system 7 may be implemented. For example, theEEC unit 2 could be designed such that it can directly send informationto ground and thus to the remote surveillance system 7. In anotherexample, the RFID reader 3 communicates directly—and not through EEC2—with the aircraft on-board communication unit 60.

Also, those skilled in the art will appreciate that other aspects of thedisclosure can be obtained from a study of the drawings, the disclosureand the appended claims. For example, while the invention has beendescribed in the drawings with respect to an aircraft unit that is anaircraft engine, the invention may be implemented in a similar manner inother aircraft units such as a Landing Gear Unit or an Engine VibrationMonitoring Unit.

All language of distinction and disparagement with respect to certainfeatures is intended to indicate a lack of preference for thosefeatures, but not to exclude such from the scope of the disclosureentirely unless otherwise indicated. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. Various features of thevarious embodiments disclosed herein can be combined in differentcombinations to create new embodiments within the scope of the presentdisclosure. Any ranges given herein include any and all specific valueswithin the range and any and all sub-ranges within the given range.

1-21. (canceled)
 22. An aircraft monitoring system, comprising: at leastone Line Replaceable Unit (LRU) installed in an aircraft unit, the LRUcomprising a Radio Frequency Identification (RFID) tag, the RFID tagcontaining stored information which consists of or comprisesID-information identifying the LRU, and an RFID reader installed in theaircraft unit, the RFID reader being located and configured to at leastintermittently automatically read the RFID tag of the at least one LRU,wherein the RFID reader is configured to transmit at least the readID-information to an aircraft communication unit for determining fromthe received ID-information if an LRU has been or shall be replaced,wherein the communication unit participates in sending theID-information to a remote surveillance system.
 23. The aircraftmonitoring system of claim 22, wherein the RFID reader is configured toread the RFID tag periodically, especially after defined time intervalsand/or upon predefined events that occur repeatedly.
 24. The aircraftmonitoring system of claim 22, wherein the RFID reader is configured toread the RFID tag upon each start of the aircraft or aircraft engine.25. The aircraft monitoring system of claim 22, wherein the RFID tag isa passive or semi-active tag, the aircraft monitoring system especiallycomprising a plurality of passive, semi-active and/or active tags,preferably comprising at least one semi-active or active tag.
 26. Theaircraft monitoring system of claim 22, wherein the RFID tag is embeddedin hardware of the LRU.
 27. The aircraft monitoring system of claim 22,wherein the RFID reader is located inside, outside or near an ElectronicControl Unit of the aircraft unit, or in that the RFID reader is aseparate component from the Electronic Control Unit.
 28. The aircraftmonitoring system of claim 22, wherein the aircraft communication unitto which the RFID reader transmits the ID-information read from the RFIDtag is an Electronic Control Unit of the aircraft unit or an on-boardcommunication unit located in the aircraft; and/or in that the aircraftcommunication unit to which the RFID reader transmits the ID-informationread from the RFID tag is designed and configured to participate intransmitting the read ID-information to the remote surveillance systemby means of a Health Monitoring system that has been implemented totransmit health information about aircraft components to the remotesurveillance system.
 29. The aircraft monitoring system of claim 22,wherein the aircraft communication unit to which the RFID readertransmits the ID-information read from the RFID tag is configured todetermine from the ID information if an LRU has been replaced and, ifso, to transmit such replacement information together with the readID-information to the remote surveillance system.
 30. The aircraftmonitoring system of claim 22, wherein the communication unit isconfigured to link ID-information regarding an LRU with at least one ofthe following additional information: accumulated hours and/or cycles ofthe LRU before removal, location of removal of the LRU, time of removalof the LRU, wherein the additional information is transmitted togetherwith the ID-information to the remote surveillance system.
 31. Theaircraft monitoring system of claim 22, wherein the aircraft unit is anaircraft engine.
 32. A method for collecting data on aircraftmaintenance, the method comprising: automatically reading at leastintermittently by means of an RFID reader which is located in anaircraft unit ID-information contained in at least one Radio FrequencyIdentification (RFID) tag comprised in a Line Replaceable Unit (LRU) ofthe aircraft unit, each RFID tag containing ID-information identifyingthe respective LRU, the ID-information being automatically readperiodically, and transmitting the read ID-information to a remotesurveillance system.
 33. The method of claim 32, wherein theID-information is read after defined time intervals and/or uponpredefined events that occur repeatedly, especially at least uponpredefined events including each start of the aircraft or aircraftengine.
 34. The method of claim 32, wherein the read ID-information istransmitted to the remote surveillance system by means of a HealthMonitoring system that transmits health information about aircraftcomponents from the aircraft to the remote surveillance system; and/orin that the ID information read from the RFID tag is interpreted todetermine if an LRU of the aircraft unit has been replaced and that thisinformation is gathered at the remote surveillance system.
 35. Themethod of claim 32, wherein ID-information regarding an LRU is linkedwith at least one of the following additional information: accumulatedhours and/or cycles of the LRU before removal, location of removal ofthe LRU, time of removal of the LRU, time to remove the LRU and installa replacement LRU.
 36. A surveillance system for collecting data onaircraft maintenance, wherein the surveillance system is configured toreceive from an aircraft communication unit ID-information regarding atleast one LRU of an aircraft unit, each ID-information being containedin an RFID tag of an LRU and identifying an LRU, the ID-informationbeing automatically read periodically, and determine from the receivedID-information if an LRU has been replaced.
 37. The surveillance systemof claim 36, wherein the surveillance system is further configured tolink a replacement information regarding an LRU with at least one of thefollowing additional information: accumulated hours and/or cycles of theLRU before removal, location of removal of the LRU, time of removal ofthe LRU, time to remove the LRU and install a replacement LRU.
 38. Thesurveillance system of claim 36, wherein the surveillance system isfurther configured to provide such ID-information or informationdeducted therefrom to service personal units for use of such informationby service personal when maintaining an LRU, and to receive from suchservice personal units additional information about LRUs and maintenancework performed thereon.
 39. The surveillance system of claim 36, whereinthe surveillance system is further configured to receive informationfrom a stock or repair facility about a replaced LRU, the stock orrepair facility identifying a replaced LRU by means of its RFID tag. 40.A software application product storable and operable in a mobile devicethat includes a graphical user interface, the software applicationproduct when executed on a processor in the mobile device beingoperative to: receive from a remote surveillance system information onat least one Line Replaceable Unit (LRU) of an aircraft unit that hasbeen or that shall be replaced, the information including ID-informationcontained in a Radio Frequency Identification (RFID) tag comprised inthe LRU, the ID-information being automatically read periodically, andprovide to the remote surveillance system information about such LRUand/or maintenance work performed thereon.